[Secessionist]

What fog formats are in current hardware? Which ones are missing from, say, the Voodoo5 or the GeForce FX?

[Davros]

I'd say none, obviously cards can do all kinds of fog but there are no dedicated units
a better question would be what fog formats are supported in current api's/drivers
and I would say all of them that were there in the past are still there now (*but then again )

Range or Radial fog
Eye-Plane fog
table fog * this may have been dropped from current drivers remember the enable fog table emulation option in nv drivers
vertex fog

edit: the enable table fog emulation was a compatibility settings as some cards/games didnt do it right

ps: found a good explanation of fog table emulation :
Fog Table Emulation: This is for 3D chips that don't support looking up the fog level by distance from the camera per pixel. Instead it emulates it by looking up the fog level at each vertex in the table and interpolating it

[sebbbi]

Then there was of course linear and exponential fog falloff. If I remember correctly, the range fog was vertex based, and table fog was pixel based. Table fog supported exponential falloff (I remember using it in my first graphics engine).

New shader based hardware can emulate all these fog modes by a few extra pixel shader instructions. Fixed function hardware fog support hasn't existed for a long time. It died at the same time fixed function T&L died. Both T&L and fog are emulated by shaders if you run and old DX version (or fixed function OpenGL) on the new cards.

[Secessionist]

Okay thanks. That's actually good to know.